Offshore drilling platform protection device

ABSTRACT

An offshore drilling platform protection device for use on an offshore oil well drilling vessel including a drilling platform supportable on a plurality of extendable legs wherein each leg is moved by a rack gear assembly, which rack gear assembly includes an otherwise exposed first gear which engages a second gear positioned in a housing having a rectangular corner opening through which the first gear extends, the protection device including first and second protective sections adapted for mounting over the first gear adjacent to the rectangular corner of the housing for the second gear, the first and second protective sections cooperating to provide an L-shaped opening which communicates with the opening at the second gear housing for protecting the first gear while allowing the first gear to mesh with the second gear.

TECHNICAL FIELD OF THE INVENTION

This invention relates to offshore drilling vessels and in particular togear assemblies for extending the legs which support a drilling platformfor such vessel and to a protective device for covering one of theotherwise exposed gears of the gear assembly.

One type of offshore oil well drilling vessel includes a platform havinga plurality of extendable legs, this type of drilling vessel sometimesbeing called a jack-up oil well drilling platform. Typically, such anoil well drilling vessel is floated offshore to the drilling site andthen the extendable legs are moved downwardly through the platform intoengagement with the bottom and thereafter, the platform is moved or"jacked" up the legs to a position above the water line. One type ofactuating mechanism for jacking these support legs includes a rack gearassembly mounted with the platform for engaging a rack gear mounted onthe legs for moving the legs up and down with respect to the platform.Naturally, it is necessary to utilize a number of gears to provideproper gear reduction between the actuation motors and the actual gearswhich engage the rack mounted on the legs in order to jack the legs upand down. The largest gear in such a rack gear assembly is commonlyreferred to as a "bull" gear. Typically, in many oil well drillingplatforms utilizing this type of leg actuation mechanism, the bull gearis exposed to the elements. Whenever it is necessary to rotate the bullgear and thus cause the bull gear to mesh with another gear, it has beennecessary to freshly lubricate the exposed gear. On some drillingplatforms, there may be as many as ten or more bull gears which need tobe lubricated each time the legs are extended and retracted. Thislubrication is essential; and therefore, critical manpower is usedlubricating the bull gears whenever it is necessary to move the legs.

SUMMARY OF THE INVENTION

It is an object of this invention to provide a protective device for usein a rack gear assembly on an offshore oil well drilling vessel toprovide needed protection and continuous lubrication for such largegears as the bull gear thus eliminating the need for additionallubrication of the gear whenever it is used. This object is accomplishedby providing the protective device of this invention, which includesfirst and second protective sections adapted for mounting over the firstor bull gear, which is positioned in engagement with a second gearalready in a rectangular housing, the first gear extending through acorner opening in the second gear rectangular housing. The first andsecond protective sections of the protective device of this inventioncooperate to provide an opening adapted for alignment with the openingin the housing for the second gear at a rectangular corner of thathousing so that the first gear may be protected from the elements andprovided with a continuous reservoir of lubrication while allowing thefirst gear to extend into meshing engagement with the second gear withinthe second gear housing.

The first protective section of the preferred embodiment of thisinvention is generally semi-circular in configuration and includes frontand rear walls connected by a first arcuate rim to form a generallysemi-circular configuration. The front and rear walls and the first rimof the first protective section each have an edge portion cooperating toform a first part of the opening for the device.

The second protective section is also generally semi-circular inconfiguration and includes front and rear walls connected by a secondarcuate rim to form a generally semi-circular configuration. Connectionmeans are provided for connecting together these first and secondprotective sections about the first gear. The front and rear walls andthe second rim of the second protective section have edge portions whichcooperate to provide a second part of the device opening. The first andsecond protective section openings cooperate to provide an L-shapedopening adapted for alignment with the opening in the housing for thesecond gear in order to provide protection to the first gear whileallowing the first gear to be in meshing engagement with the second gearlocated in the second gear housing.

These features and other features of the protective device of thepreferred embodiment of this invention will be described in detail inthe Description of the Preferred Embodiment to follow, with the claimsfollowing the Description of the Preferred Embodiment setting forth thesubject matter for which patent protection is sought.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front view of a part of the rack assembly of an offshoredrilling vessel illustrating the protective device of the preferredembodiment of this invention in use;

FIG. 2 is a side view of the protective device taken in section alongline 2--2 of FIG. 1;

FIG. 3 is a top view of the protective device of FIG. 1;

FIG. 4 is an isometric view, partly in section, of a set of theconnector elements of the mount means for mounting the protectivedevice;

FIG. 5 is a rear, isometric view of the protective device connectedtogether;

FIG. 6 is a sectional view taken along lines 6--6 of FIG. 1 of theconnection means for connecting together the first and second protectivesections of the protective device; and

FIG. 7 is a side view of an alignment member for aligning the connectionof the second cover section to the first cover section.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to the drawings, the letter P generally designates theprotective device of the preferred embodiment of this invention. Theprotective device P is designed for specific use on an offshore oil welldrilling vessel such as a jack-up vessel which includes a drillingplatform supportable on a plurality of extendable legs. In one type ofoffshore oil well drilling platform of the jack-up variety, theextendable legs are jacked up and down by means of a rack gear assemblywhich inclues a number of actuation gears mounted on the drillingplatform for engagement with a rack gear mounted on the extendable leg.Part of such a rack gear assembly, generally designated by the letter R,is illustrated in FIGs. 1 and 2.

The rack gear assembly R as illustrated in FIGS. 1 and 2 includes a backwall or motor housing wall 10 having shaft 11 extending therethroughwith a main or "bull" gear G-1 mounted on the shaft 11 for rotation. Theshaft 11 may be connected to a motor drive (not shown). The bull gear,referred to herein as a first gear, G-1 is defined as being positioned adistance d away from the motor housing or back wall 10. The rack gearassembly R further includes a second gear G-2 smaller in overalldiameter than the gear G-1, positioned in a rectangular housing 12 alsomounted on the motor housing wall 10. The rectangular housing 12 is aprincipally enclosed housing which includes side walls 12a, 12b and 12c(the top wall not being shown) and a front wall 12d which cooperateswith the motor housing wall 10 to provide a substantially enclosedhousing for the second gear G-2. The second gear G-2 is mounted on ashaft (not shown). The second gear housing 12 is provided with a corneropening 14, which is defined as being L-shaped, formed by a recesspartly in wall 12a and partly in wall 12b, which opening 14 allows forpositioning of a part of the first gear G-1 in meshing engagement withthe second gear G-2 in the second gear housing 12. The L-shaped opening14 is therefore formed at a rectangular corner of the generallyrectangular second gear housing 12 and allows for the rotation or travelof the gear teeth on the perimeter of the first gear G-1 through theopening 14 so that the gears G-1 and G-2 are in meshed engagement. Inthe rack gear assembly R, additional gears (not shown) may be mountedwithin the cover 15, which s positioned outside of and mounted onto thefront wall 12d of the second gear housing 12.

Generally, the protective device P is provided for protecting theotherwise exposed first gear G-1 while allowing a portion of this gearto mesh with the second, housed gear G-2 within the second gear housing12 and further, the protective device P provides a continuouslubricating reservoir generally designated as 16 for continuouslylubricating the gear teeth of the gear G-1. The protective device Pincludes first and second protective sections 17 and 18 which areconnected together by connection means generally designated as 19 inposition over the first gear G-1 and which are attached to the motorhousing wall 10 by a mount means generally designated as 20.

The first protective section 17 is generally semi-circular inconfiguration when viewed from the front and includes a semi-circularfront wall 17a, an arcuate first outer rim 17b and a semi-annular gearwall 17c. The semi-circular front wall 17a includes a straight bottom ordiagonal edge 21a and a generally semi-circular outer edge 21b. Thefirst rim 17b, which is also semi-circular in curvature, is welded orotherwise attached to the outer semi-circular edge 21b of the frontwall. The width of the first rim 17b is greater than the width orthickness of the gear G-1. The generally semi-annular rear wall 17cincludes a generally semi-circular outer edge 22a welded or otherwiseattached to the other edge of the first rim portion 17b and an inneredge 22b, to which is attached a spacer rim portion 23 which extendsrearwardly and is adapted to actually engage the motor housing wall 10.

The front wall 17a, first outer rim 17b and rear wall 17c cooperate toprovide a first opening portion 0-1 of a generally L-shaped openinggenerally designated as 0. The first opening portion 0-1 of the opening0 is formed by the chord-like edge 21c machined vertically and at aright angle with respect to diagonal front wall edge 21a, which is shownhorizontal. The first rim 17b terminates in a transverse edge 21daligned with the vertical, chord-like edge 21c of the first wall. And,the first part of the opening 0-1 is further formed by the vertical edge22c of the annular, rear wall 17c. The edges 21c, 21d and 22c arealigned in a vertical plane to provide the first part 0-1 of thegenerally L-shaped opening 0.

Referring to FIG. 7, an alignment member 24 is welded onto the bottomportion of the first rim 17b for assisting in the alignment of thesecond protective section 18 with the first protective section 17 duringassembly. The first rim 17b terminates in a bottom edge 21e which isaligned with the diagonal bottom edge 21a of the front wall 17a. Thealignment member 24 is welded in a position to extend downwardly belowbottom rim edge 21e in position to engage the rim portion of the secondprotective section 18N.

Referring to FIGS. 1 and 6, the connection means generally designated as19 includes a horizontally extending angle member 25 which is weldedonto the bottom part of the front wall 17a in position such that flangeportion 25a of the angle member 25 is aligned with and extends outwardlyfrom bottom diagonal front wall edge 21a.

The second or bottom protective section 18 includes a generallysemi-circular front wall 18a, a second rim 18b and a generally annularrear wall 18c, which rear wall is on a plane parellel to the plane ofthe front wall. The front wall 18a, second rim 18b and rear wall 18ccooperate to provide the reservoir 16 and further to provide the secondpart 0-2 of the generally L-shaped opening 0, which is formed when thefirst and second protective sections 17 and 18 are connected togetherabout the gear G-1.

The generally semi-circular front wall 18a includes a generallysemi-circular outer edge 26a and a diagonal, straight edge 26b. Theouter, generally circular edge 26a of the front wall 18a is welded orotherwise attached to the second outer rim 18b which has a width equalto that of the first rim portion and is thus wider than the width orthickness of the first gear G-1. The rear wall 18c includes a generallysemi-circular outer edge 27a having the same radius as the outer edge26a of the front wall 18a, the outer edge 27a being welded or otherwiseattached to the second rim portion 18b. The generally annular rear wall18c further includes an arcuate inner edge 27b which is generally curvedsuch that the lowest point, or apex of the curve, located at 27c, isapproximately below the common center point for the radii (to be furtherdiscussed, infra) which generate the generally semi-circular outer walledges 26a and 27a. The rear wall 18c cooperates with the second rimportion 18b and front wall 18a to provide the reservoir generallydesignated as 16 which may house a lubrication fluid such as grease ofsufficient depth to immerse the gear tooth portion of the gear G-1during a bottom arc of the rotation of the gear G-1. A drain plug 28 ismounted in the second rim 18b to allow for the draining of thelubricating fluid such as grease whenever necessary. Further, a entryvalve 29 is mounted in the front wall portion at a height generallyaligned with the bottom apex 27c of the inner rear wall edge 27b toallow for the use of any suitable grease injection pump for filling thereservoir 16 with grease or other lubrication fluid.

The second part 0-2 of the generally L-shaped opening 0 is actuallyL-shaped itself. The opening 0-2 is provided by L-shaped edges formed inthe front and rear walls 18a and 18c. The front wall 18a includes avertical edge portion 30a which is alignable with the vertical edgeportion 21c of the front wall 17a of the first protective section 17.The front wall 18a of the second protective section 18 further includesa horizontal edge 30b which intersects the vertical edge 30a at a rightangle. A first angle member 31 is welded at the vertical edge 21c of thefirst protective section front wall 17a. And, a second angle member 32is welded onto the vertical edge section 30a of the second protectivesection front wall 18a so that the flanges of the angle members 31 and32 are aligned to provide a common abutment face for engaging the sidewall 12a of second gear housing 12. A third angle member 33 is weldedonto the horizontal edge section 30b for engaging in part an outsideportion of the lower or bottom side 12b of the second gear housing 12.

The rear wall 18c includes a vertical edge portion 34a which intersectsa horizontal edge portion 34b to provide a L-shaped edge which isaligned with the corresponding L-shaped edge provided by edges 30a and30b in the front wall 18a. Finally, the second outer rim portionincludes an upper end edge 35 which is aligned with the horizontal edges30b and 34b to also engage the bottom side member 12b of the second gearhousing 12.

In the preferred embodiment of this invention, the generallysemi-circular shape of the front wall 18a includes a tangentialextension section 38a which is formed by the horizontal edge 30b and bya tangential extension 38b of the outer generally semi-circular edge 26aof the front wall 18a of the second protective section 18. Similarly,the rear wall 18c includes a tangential extension section 29 formed bythe horizontal edge 34b and a tangential extension 39a of the outer rearwall edge 27a. This tangential extension section allows the horizontallength of the edges 30b and 34b of the front and rear walls 18a and 18c,respectively, to be longer thus providing a landing ledge to abut thebottom second housing side 12b. Referring to FIG. 1, it is again notedthat the opening 14 formed by the second housing side walls 12a and 12bis actually L-shaped itself and therefore, it is necessary for thehorizontal length of the ledge provided by edges 30a and 34b to besufficiently long to engage the bottom side wall 12b of the housing 12in an area beyond the edge 12e which identifies one end of the recess inthe side wall members 12a and 12b which provide the L-shaped opening 14.In this manner, the L-shaped opening 0 is formed by the combination ofthe openings 0-1 and 0-2 in the first and second protective sections 17and 18, respectively. The opening 0 is adapted to be aligned with theL-shaped opening 14 in the second housing 12 in order to allow forrotation of the gear tooth portion of the gear G-1 within the housing 12in meshing engagement with the gear G-2.

Referring to FIGS. 1 and 6, the connection means generally designated as19 further includes the angle member 40 mounted adjacent to the diagonaledge 26b of the second protective section front wall 18a in a positionsuch that outwardly extending flange portion 40a of the angle 40 isaligned with the top diagonal edge 26b. In this manner, when the firstand second protective sections 17 and 18 are joined together, the flangeportions 25a and 40a abut such that bolt assemblies 41 may be mounted inaligned openings in the flange portion 25a and 40a thus providng theconnection means 19 which connect together the first protective section17 and second protective section 18.

There have been a number of semi-circular peripheral edges described.For example, the outer edge 21 of the front wall 17 is generallysemi-circular and may be defined as being generated by a radius rrotated about a center point 42. The outer semi-circular peripheral edge22a of the rear wall 17c has the same radius and similarly, thecurvature of the outer rim 17b has substantially the same radius, also.That same radius r provides the peripheral edges 26a on the front wall18a of the second protective section 18, the same radius r generatingthe outer edge 27a of the rear wall 18c. Of course, the tangentialsection formed by wall portions 38a and 39 are not generated along theradius r, but rather, may be defined as generated in an approximatelytangential direction to the radius r to that side of the protectivedevice sections 17 and 18. The center of all of these outer peripheraledges defined as being generally semi-circular is common at point 42. Anopening may also be provided about point 42, such opening, identified as43, being provided to allow for a spindle or other center extension ofthe gear G-1 or gear shaft 11.

The mount means previously identified as 20 is provided for attachingthe joined first and second protective sections 17 and 18 to the motorhousing wall 10. The mount means 20 includes a plurality of sets ofcircumferentially spaced first and second connector members 45 and 46spaced about the first and second rim portions 17b and 18b. Connectormembers 45, which are L-shaped angle members, are each welded onto theouter rims 17b and 18b and extend rearwardly and include a portion 45awhich extends rearwardly beyond the rim edges. The angle portion 45aextends rearwardly a distance equal to the width of the spacer rim 23 sothat the end of each of the connector member portions 45a issubstantially adjacent to the motor housing wall 10. The mount means 20further includes a plurality of two second connector members 46, whichare also L-shaped angles, which are adapted to be welded or otherwiseattached to the motor housing wall 10 at circumferentially spacedintervals for alignment with an abutment against the angle member endportions 45a. The connector members 46 are positioned such that oneflange 46a thereof is adapted to align with and mate against a flange45b on each of the extended portions 45a of the connector members 45 sothat bolt assemblies 47 may extend through openings aligned in theoppositely facing faces of flanges 46a and 45b.

In operation and use, the protective sections 17 and 18 are mounted overthe gear G-1 and the flange faces 25a and 40a are connected together bybolt assemblies 41 of the connection means 19. In making such mounting,this first protective section 17 is mounted over the first gear G-1 andthe connector 45 on rim 176 are aligned with and bolted to connector 46.The second section 18 then positioned under the first section 17 and therim 186 is aligned by engagement against alignment member 24. Theconnector members 45 on rim 186 are then aligned with the connectormembers 46 attached to the motor housing wall 10 in order to receivebolts for actually bolting the connected sections 17 and 18 to thehousing wall 10. The L-shaped opening 0 provided by opening portions 0-1and 0-2 of the joined protective sections 17 and 18 is aligned with theopening 14 in the second gear housing 12 in order to allow the gear G-1to engage the gear G-2 within the confines of the second gear housing12. The vertical edges 21c and 22c of the front and rear walls 17a and17c, respectively, of the first protective section 17, actually abutagainst and engage the second housing side wall 12a. Similarly, thehorizontal edges 30b and 34b of the front and rear walls 18a and 18c,respectively, of the second protective section 18, engage the bottomside wall 12b. In this manner, the gear G-1 is allowed to rotate withinthe housing 12 for the gear G-2 and lubrication fluid which may besplashing is held within the confines of the reservoir 16.

The foregoing disclosure and description of the invention areillustrative and explanatory thereof, and various changes in the size,shape and materials as well as in the details of the illustratedconstruction may be made without departing from the spirit of theinvention. The disclosure has been directed to a particular environment,the protective section of an otherwsie exposed gear which forms part ofa rack assembly on an offshore oil well platform and which gear mustmesh with a gear positioned in a housing. It should be understood thatthe protection device of this invention may have application in otherenvironments where gear protection is needed.

I claim:
 1. On an offshore oil well drilling vessel including a drillingplatform supportable on a plurality of extendable legs, wherein each legis moved by a rack gear assembly which includes an otherwise exposedfirst gear which engages a second gear positioned in a housing,protective device, comprising:first and second protective sectionsadapted for mounting over such first gear, which is mounted on a shaftextending through a back wall, said protective sections being adaptedfor mounting adjacent to second gear housing, which second gear housingincludes an opening on one corner thereof in which opening is positioneda portion of such first gear for meshing engagement with said secondgear; said first protective section being generally semi-circular inconfiguration and including front and rear walls connected by a firstarcuate rim to form a generally semi-circular configuration, said frontand rear walls and first rim having edge portions cooperating to form afirst cover section opening; said second protective section beinggenerally semi-circular in configuration and including front and rearwalls connected by a second arcuate rim to form a generallysemi-circular configuration, said front and rear walls and second rimhaving edges cooperating to provide a second cover section opening forcooperating with said first cover section opening to provide an L-shapedopening to be positioned adjacent to the corner opening of such secondgear rectangular housing; protective section connection means mountedwith said first and second cover sections for connecting said coversections together over the first gear; and mount means for mounting saidfirst and second protective sections onto such first gear back wall. 2.The structure set forth in claim 1, wherein said protective sectionconnection means includes:said front wall of each of said generallysemi-circular protective sections including a diagonal edge having anelongated flange, which flanges are connected together to connect saidfirst and second protective sections together.
 3. The structure setforth in claim 1, wherein said mount means includes:a plurality of firstconnector members being mounted on said first and second rim portions atcircumferentially spaced points, said first connector members extendingtransversely across said first and second rims and extending rearwardlyfrom said rear wall portion; a plurality of second connector membersadapted for attachment to such back wall for said first gear incircumferential positions for alignment with said first connectors; andbolt means for connecting aligned first and second connector memberstogether.
 4. The structure set forth in claim 3, wherein:said first andsecond connector members are L-shaped angles aligned for engagement onoppositely facing surfaces.
 5. The structure set forth in claim 1,wherein:said edge portions of said front and rear walls and said firstrim of said first protective section which form said first cover sectionopening being in the same plane; and said edge portions of said frontand rear wall of said second protective section having first and secondsegments at right angles to form an L-shaped opening adapted to engagethe corner of such second gear housing.
 6. The structure set forth inclaim 1, including:said front wall of said first protective coversection being generally semi-circular in configuration; said rear wallof said first protective cover section being annular in configuration;and a spacer rim portion connected to said annular rear wall portion andbeing adapted to be positioned adjacent to the back wall.
 7. Thestructure set forth in claim 6, wherein said mount means includes:aplurality of first connector members being mounted on said first andsecond rims at circumferentially spaced points, said first connectormembers extending transversely across said first and second rim portionsand extending rearwardly from said rear wall portion; a plurality ofsecond connector members adapted for attachment to such back wall forsaid first gear in circumferential positions for alignment with saidfirst connectors; bolt means for connecting aligned first and secondconnector members together; and said spacer rim portion and said secondconnector member having substantially the same thickness.
 8. Thestructure set forth in claim 1, including:said front wall of said secondprotective section being generally semi-circular in configuration; andsaid rear wall of said second protective section being generally annularin configuration and cooperating with said front wall and said secondrim portion to form a grease reservoir through which said first gear isrotated to be continually lubricated.
 9. The structure set forth inclaim 1, including:an alignment member attached to said first rim ofsaid first protective section and extending diagonally to engage saidsecond rim portion of said second protective section for alignment ofthe protective sections for connection together.